class_docstr: Tests using the Moses multi-bleu script to calcualte BLEU score
    
code: def test_empty(self):
      self._test_multi_bleu(
          hypotheses=np.array([]),
          references=np.array([]),
          lowercase=False,
          expected_bleu=0.00,
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import numpy
  import tensorflow
  from seq2seq.metrics import bleu
  from seq2seq.metrics import rouge
  from seq2seq.metrics.metric_specs import BleuMetricSpec
  from seq2seq.metrics.metric_specs import RougeMetricSpec
label_desc: Use image node_id 3 for calling the TestMosesBleu obj's underlying member method code with example usage: obj.test_empty() without return types